1. Technical Field
The present invention is directed to testing equipment for testing integrated circuits before installation onto circuit boards.
2. Background
Testing microcircuits before soldering them onto circuit boards is essential to making products with a low failure rate. Defective microcircuits are difficult or impossible to remove from a circuit board, so installing a defective microcircuit typically requires scrapping the entire circuit board. In general, testing of an individual microcircuit involves temporarily connecting test contacts to the microcircuit terminals, and then using special test circuitry connected to the test contacts to operate the microcircuit to test the microcircuit functions.
Microcircuits are provided in a number of different package types. The means for connecting test contacts to a particular type of microcircuit depends on the type of package enclosing the microcircuit and the type of contacts carried by the package. Of course, making good contact between every one of the test contacts and the associated microcircuit terminal is very important, since a bad test connection to even one microcircuit terminal will indicate the microcircuit as defective even though the microcircuit may in fact be fully functional.
The type of package of interest is a leaded microcircuit or integrated circuit (IC) package. Another is leadless which has small connector pads along the edges of one face form solder terminals by which the package is electrically and mechanically connected to the circuit board. Internal wiring connects the internal microcircuit to the solder terminals. Hereafter the term “package” will refer to both leaded and leadless packages unless otherwise stated or the context clearly indicates otherwise. Further, the microcircuit under test is conventionally referred to as the “DUT”, that is, device under test.
To test such ICs, a test socket is built for that particular lead configuration and shape. An insert (generally a robot) will pick an IC part from a bin, oriented more or less correctly for insertion and then insert it into the test socket.
This operation happens quickly and not necessarily under ideal conductions. Alignment of the inserter and socket are not always perfect or the alignment force is outside of specification.
Misaligned insertions or improper force can destroy either test socket, its contact pins, the IC or all of the above. Further, damage caused by one bad insertion can leave behind debris which destroys or mis-tests subsequent ICs.
Therefore it is important to find ways to compensate for inserter errors.